Houseguests
by saltedpin
Summary: Skyfire sets himself up for a fall. Post-series 3, post-Ghost in the Machine. Warnings for a somewhat dark Skyfire.


**WARNING:** Some violence and mature themes. Starscream/Skyfire (sort of ;).

* * *

><p>Slowly, Skyfire turned the fern leaf over beneath the microscope, making a small noise of wonderment as he inspected the curled, self-repeating patterns contained within its structure. Since the formal cessation of hostilities between the Autobots and the Decepticons he'd been able to return to his first love – organic biology – now with the advantage of actually having lived on a planet entirely populated by organic things.<p>

Hearing Starscream's derisive snort, however, he was reminded that not everyone shared his enthusiasm for his pet subject. _It's just an iterated function system, Skyfire, and not even a very complex one. I could have programmed one for you in three breems, if I'd known you were that interested._

Skyfire turned the leaf over again. _It grew like this. It wasn't programmed – well, not in that sense, anyway,_ he explained, adjusting the microscope's magnification slightly.

Skyfire felt Starscream's interest spike for a moment, before it was hastily covered up with his usual petulance.

_So what?_

_We don't even have the taxonomy to describe some of these. Can you imagine? Curved structures being more intuitive than smooth ones, fractals being more natural than straight lines? _

_No, and I don't want to,_ came Starscream's sulky reply.

Skyfire smiled inwardly despite himself, laying down his tweezers and slightly flexing the fingers on his right hand.

* * *

><p><em>Skyfire had heard the stories of Starscream's reappearance, and, despite the source – a notorious Decepticon turncoat – he had believed them. The fact that Rodimus Prime himself had later started swearing to Primus that he had run into Cyclonus, speaking in that all-too-recognisable voice and behaving entirely out of character, had only served to cement what Skyfire already knew. <em>

_Despite this, he delayed – a delay during which Metroplex's eyes had been stolen, Trypticon had gone on a short, uncharacteristically eloquent rampage, and Unicron had been reawakened, however briefly, for reasons that remained a mystery as far as the Autobots were concerned._

_But Decepticon headquarters leaked like a sieve these days thanks to scores of disgruntled Sweeps, and Skyfire had little trouble discovering what had happened, and where to follow._

* * *

><p>When Skyfire returned to the Autobot fold, long after he first left it, most of his former comrades accepted him back into their ranks only because Optimus Prime did so. The question of what, exactly, Skyfire had been <em>doing<em> this whole time was never adequately explained to them, nor the reason for his sudden return.

That he was regarded with mistrust, coated by a thin layer of tolerance, did not seem to bother Skyfire – conversely, the fact that he was left mostly to his own devices seemed to suit him entirely too well. Mechs who had known him well back on Earth – Perceptor, Beachcomber, Seaspray – all agreed there was something indefinably _different_ about the Skyfire who now walked among them, though so far, apart from his tendency to sit for hours on end in silence, his lips occasionally twitching into a smile, none of them had been able to pinpoint exactly _what_ was different.

Skyfire, when he found out via Inferno (genial to a fault – he thought Skyfire would find it _funny_) that Red Alert wanted to bug his quarters and attach a covert security detail to him, had been guiltily grateful to also learn that Optimus had expressly forbidden it, saying that Skyfire had proved his worth to the Autobots repeatedly, and deserved their trust. What allegiances he had had in the past were just that – the past.

(Starscream snorted derisively when he found out about it. _Prime never learns,_ he said, sounding disgusted. _He always gives the benefit of the doubt. Megatron just would have beaten the truth out of you._)

With the exception of Red Alert, the Autobots were happy to let Skyfire drift in and out of the laboratories, keeping to his own schedule, and occasionally take trips offworld to Primus-only-knew-where. He would return with samples of organic things and spend the next few cycles entirely engrossed in them, becoming even more introverted than usual. On the few occasions when Perceptor attempted to join him in his activities, Skyfire, though civil and courteous, was obviously bothered by the intrusion, and after a while, Perceptor, too, withdrew his company.

* * *

><p><em>Skyfire had theorised there was a reason behind Starscream's choice of host bodies. Not unstable, overbearing Galvatron or self-assured, narcissistic Octane, but loyal, downbeaten Cyclonus, cowardly Scourge, and mentally underprovided Trypticon – and even then, Trypticon seemed to have managed to put up some rudimentary resistance, just through sheer brute force. <em>

_And Skyfire had two advantages over Cyclonus, Scourge and Trypticon – the first was that he was prepared for what was about to happen. The second was he_ knew _Starscream._

* * *

><p>Leaving the laboratory, Skyfire headed down the corridor towards his quarters, badly needing to recharge after the long day of both mental and physical exertion. One side effect of the task he had set for himself was requiring much a longer recharge time than he ever had previously – the mental strain alone was enough, let alone the times when the struggle occasionally became physical.<p>

On his way down the corridor he paused briefly to nod to Ultra Magnus, who was heading rapidly in the other direction. A moment later, Starscream predictably piped up, his voice seeping into Skyfire's consciousness, more fluidly even than an internal commlink.

_I don't know why you ever came back to these cretins,_ he said, contemptuously. _If it hadn't been for Megatron's bungling we would have wiped the floor with them vorns ago. They're weak_ – useless.

Skyfire smiled tightly. _They accepted me back after all this time. They don't question me – they just let me be._

Inside his mind, Starscream laughed. _And what if they knew the secret you're carrying around in your head? Do you think your precious Autobot friends would be so accepting of you_ then?

* * *

><p><em>Skyfire had tracked him across the planet, knowing that sooner or later, even Starscream would have to give up. Eventually he had found him, on his hands and knees at the base of a mountain, energon leaking from the side of his head, one leg mangled, and a wing that had been shorn off at the root. The energon leaking from his mouth spoke of internal rupturing that was likely irreparable. The only question was how long it would take him to die.<em>

_Despite Starscream's obviously sorry state, Skyfire had approached him with caution, laser rifle held in front of him. Starscream hadn't even looked up as he approached; he had to have known what was going to happen._

_"You know I can't let you go," Skyfire had said when he got close. "Not this time. Not after_ this._"_

_Starscream, energon flowing freely from his mouth, had laughed quietly before answering. "In that case, you'd better kill me," he said, his voice sounding even harsher than usual, struggling out of his damaged vocaliser._

_Skyfire raised the laser rifle and held it to Starscream's temple. Starscream bowed his head in the mockery of submission that came so naturally to him now, a small smile snaking across his lips in the second before Skyfire pulled the trigger. The laser rifle report echoed off the cliff, and Starscream slumped over._

_He paused, and waited for Starscream's sense of irony to do the rest._

* * *

><p>It was at times like this that Skyfire allowed Starscream more free rein than was probably advisable – he felt him slowly spread out and feather through his neurocircuitry, and the effect was not unlike the early stages of over-energising.<p>

_Starscream..._

Skyfire, safely behind the closed doors of his quarters, arched his back and scraped the tips of his wings against the wall behind him, one hand slowly running down the seams in his side, stroking the cabling exposed by the gaps in his armour, the other curling to press against the sensors in his fuselage.

The first time they had done this it had been at Starscream's instigation, and Skyfire hadn't been at all surprised to find he was already an expert at it – Starscream was nothing if not a fast learner.

_What would you do... if I had my own body?_ Starscream's voice slid slowly through the blocks of his memory banks, finding every imaginary scenario, every secret Skyfire had ever kept hidden about what he _would have liked_ to have done all those vorns ago, unlocking them and spreading them wide. _Hmm. Put me on my knees, make me beg?_ There was a slight pause as Starscream pushed deeper. _Ha! With an electroprod? Why Skyfire, all you had to do was ask..._

Skyfire bit his lip, moaning from deep in his throat, while in a movement that was only half his own his hand slipped from his fuselage and down, stroking the sensitive inside of his thigh.

_Oh, here's something..._ Starscream turned a corner and the next moment a surprisingly vivid image of Starscream, mouth open wide, arched beneath Ultra Magnus flashed through Skyfire's mind. His optics flashed back online.

"Starcream!" Skyfire cried just a little too loudly, yanking his hand away from his thigh.

Starscream almost purred. _There's no point in acting scandalised, it's all here... you think I wouldn't find out about your voyeurism kink?_ Over the next few seconds Starscream accessed and displayed image after image – Starscream pressed face-down down the floor, screaming his vocaliser out while Ultra Magnus bent over him, Starscream braced against a wall, the flat of Ultra Magnus' left hand pushed into the middle of his back while the other bent one of his wings backwards, Starscream, head down, energon chains encircling his throat, scrabbling at Ultra Magnus' feet...

_Hmph,_ Starscream reflected appreciatively, finding a scenario he particularly liked and playing it in full, stretching it out far beyond anything Skyfire had imagined, _Skyfire, I never knew you had it in you._

Skyfire's optics flickered off again, his hand sliding back between his legs and a tiny groan escaping his lips as he brought himself slowly to overload to the image of Starscream bent between Ultra Magnus and Galvatron, simultaneously jacked into both, writhing and panting, oil smeared across his face.

* * *

><p>"Skyfire?"<p>

Skyfire looked up from the small snail he had been dissecting to see Ultra Magnus standing in the doorway, looking vaguely uncomfortable about having interrupted him.

"Can I help you?" Skyfire asked politely, laying aside his laser scalpel.

"Perceptor's offworld at the moment on a geology study," Magnus explained, leaving the doorway and gesturing for Skyfire to follow him down the corridor. "But we've just got the test results from a new power generator we've been trying out, and it's urgent we get this up and running as soon as possible. Would you mind having a look at them for us?"

"No, no, of course not," Skyfire murmured, entering the command centre, Red Alert turning to scowl unpleasantly at him at he did.

_Oh, Red Alert,_ Starscream sniffed, _Skyfire, did I ever tell you about the time I –_

_Shut up, Starscream,_ Skyfire cut in, shaking his head slightly as he sat down at the computer, and could not resist adding, _if you ever told me about all 'the times you' we'd be here until next year._ Skyfire could not help but smile slightly as Starscream's appreciative chuckle seeped through his neurocircuits. Behind him, Red Alert and Ultra Magnus exchanged a glance.

_Sometimes I worry I'm rubbing off on you._ Starscream sounded smug, and pressed experimentally against the edges of Skyfire's modified cranial chamber. _So, who rigged this up for you? Perceptor? Wheeljack?_ A pause. _Not Ratchet, obviously. _

_No, I –_ Skyfire stopped midsentence, suddenly remembering that both Wheeljack and Ratchet were dead, and who had made them that way. After a moment, he fired up a container programme, and he felt Starscream retreating, however unwillingly, from the places he had invaded.

_Oh, don't be like that,_ Starscream said sulkily. _That was ages ago. And we were at war. I couldn't very well defy Megatron._

Skyfire ignored him, letting the absurdity of that statement linger, and continued entering the data.

_Out of interest, what were your original plans? I hardly think you intended _this_ as a permanent solution,_ Starscream said. There was another press on the side of his consciousness. _So I can only assume the reason you haven't evicted me yet is that you enjoy my company._

_I hadn't thought about what to do next,_ Skyfire almost-lied: his research hadn't thrown up any reasonable alternatives, indestructible sparks not exactly being a common phenomenon amongst Transformers - he hadn't even been sure the containment measures he had jerry-rigged inside his own skull would be adequate – but the real truth of matter was that he had stopped looking. After so many vorns, the closeness he had craved, to have Starscream simply _there_ and unable to deny him –

"Skyfire?" Ultra Magnus's voice cut into his reverie, and he jumped visibly. "Are you okay?"

Skyfire looked across at Ultra Magnus's face, uncomprehending for a moment or two.

"Yes. Of course. I'm fine, Magnus."

He attempted a reassuring smile.

"It's just you seem a little distracted," Magnus said, all severe concern, putting a hand on Skyfire's shoulder. Unhelpfully, Starscream chose that moment to flash up an image of Ultra Magnus from the night before, hands on Starscream's hip joints and pounding him into the –

Skyfire coughed up some static before finding his vocaliser.

"No, it's just something I'm working on. It's... it's complicated. I'm having trouble with it," he said. "I guess I'm letting it get to me – you know how it is." Skyfire's smile thinned slightly.

Behind him, he heard Red Alert mutter something quietly to himself. Ultra Magnus held his gaze for a moment or two longer, before dropping his arm and returning to his station.

_Look,_ Skyfire thought viciously as he returned to the data he was supposed to be analysing, _if you're going to talk, can you at least be helpful?_ He opened a spreadsheet and tapped at some of the energy readings. _Some of these results are anomalous. I've been looking, but I can't see if there's any pattern. Any ideas?_

There was a long pause before Starscream answered. _I can't get access to the files. You're going to have to let me out of here so I can see._

Skyfire hesitated, before slowly lowering the defensive walls he had raised. _What do you think?_

Suddenly, without warning, Skyfire felt his right arm move, and slam itself down into the desk in front of him, making a significant dent and leaving the computer banks below sparking. Vaguely, he was aware of an alarm going off and Red Alert shouting something, before Ultra Magnus body checked him out of his chair, Skyfire's comparatively huge size compensated for by Magnus' soldier's strength and Skyfire's minimal control over his own faculties.

Raising his head from the floor and turning it to smile snakishly up at Magnus, Skyfire heard himself say – oh Primus in _Starscream's voice_ – "Well now, this is fun."

Skyfire could only hope the blaring klaxons were loud enough to have drowned it out – though he was probably hoping for too much, given the way Magnus started back, surprise widening his optics.

Mentally gritting his teeth, Skyfire forced himself to fire up every emergency protocol he had, shutting down neutral pathway after neural pathway, cutting off Starscream's rapid advancement and raising software firewalls to keep him stuck. It was too late, though – Starscream had already got into his awareness cortex and was moving the fingers on his left hand – about as much as he could manage at the moment, with Skyfire's CPU shut off from most of his neurocircuitry – and Skyfire knew the only solution was to do a hard restart of his mainframe, and hope that the resulting shock would jar Starscream sufficiently to keep him out until his recovery systems could rescue whatever had been corrupted.

Leaning with his elbow pressed into the back of Skyfire's neck, Ultra Magnus felt him jerk for a moment, before settling, limp, beneath him. A moment ticked by and Red Alert managed to shut off the alarm system, and then Magnus felt the life return to the great body beneath him. Skyfire's optics flickered for a moment, and the slack jaw snapped shut.

He and Ultra Magnus looked each other in the eye for a moment, before Skyfire turned his face away.

"Skyfire," Magnus's mouth was close to his audial, "what just happened?"

Skyfire opened his mouth to answer when Starcream suddenly sputtered back to life.

_What – what just happened?_ he demanded, sounding totally outraged, and as if he had full right to be.

Feeling the last of his systems come back online, Skyfire quickly ran the containment programmes and began the process of locking Starscream down, looping him around a subroutine and closing any path out.

The reaction was immediate – the mental equivalent of a cower, before Starscream's pleading voice came filtering through to him. _Please, Skyfire – I'm sorry. I won't do it again – I just... I just – please. Think about it. You and I, we could –_

_I'm sorry, Starscream,_ Skyfire said. _I've told you._

_Skyfire, I –_ Starscream's voice cut out, and Skyfire slowly turned his head to look at Ultra Magnus again.

"I'm fine, Magnus," he said, wriggling his fingers slightly to test if they still worked. "I – I should have said. I've been glitching since I got back from that last trip. I must have, uh, picked something up," he tried to smile knowingly at Magnus, wondering how anyone could be fooled by the idea that he would have networked with some virus-infected whore-bot, but nonetheless felt the pressure on the back of his neck ease up, and Ultra Magnus allowing him to sit up straight.

"Glitching," Magnus said flatly, looking him in the face. "You know you're supposed to go straight to First Aid with these sorts of things."

"I know. I guess I was... embarrassed," Skyfire finished lamely. Behind him, he could hear Red Alert start to mutter again, before a sharp glance from Magnus cut him off. "I'll go straight to the medbay, right now," Skyfire offered, hoping that Magnus's essentially honourable nature, would, like Prime's, override his suspicion.

Magnus stared at him for a long moment before looking away. "Fine. Get yourself to medbay. Now. I'll be checking in four hundred astroseconds to see that you've got there okay." He paused. "Four hundred astroseconds, Skyfire," he said again.

"I'm going, I'm going," Skyfire feigned humbled embarrassment as he stood and walked out to the corridor, and heard Red Alert mutter 'We should tell Prime,' just before the door snapped shut behind him.

For a moment, Skyfire leaned back heavily against the door. Magnus was not stupid. Prime would be informed, and Red Alert would get his way this time, and then it would be only a matter of time until he was found out. There was a choice now: leave the Autobots for good, or lose whatever he had left of his life with Starscream. The pain of the realisation that Starscream had probably intended to force his hand like this almost made his knees buckle.

Four hundred astroseconds to decide.

The end.


End file.
